Multispectral camouflage for modern warfare must keep pace with the technical development of sensors while accommodating the demand for high mobility.
For one, today's armies have high requirements when it comes to mobility. In addition, the technical possibilities of multispectral reconnaissance and target assignment have widened to a considerable degree with the miniaturization of sensors and the emergence of new platforms such as the cost-effective minidrones. This technology must also keep pace with modern means and use ultra-modern technologies if camouflage is to remain a serious means and fulfil its objective. Of particular interest in this context is today camouflage against all-weather radar sensors or thermal infrared sensors, which enable reconnaissance even at night.
Today, fully developed mobile camouflage kits, which are produced to fit perfectly onto the vehicle surface, are offered commercially. These camouflage kits from various textile materials are effective in visual camouflage by way of an appropriate color scheme and in RADAR by way of scattering or absorbing materials. In thermal infrared, an effect is also achieved by the textile upper material being provided with a sheet cut which assumes the air temperature in the airflow during travel. The upper material is sewn onto an insulation layer or other textile material, which insulates the surface temperature of the vehicle from the upper material. In addition to the convective effect for matching the signature to the environment, the textile upper material can additionally have the property of reduced thermal emissivity, which ensures that portions of the cold sky are reflected. The system thus described already has a decent effect, especially as compared to non-camouflaged vehicles. With respect to the technological development on the sensor side, however, it is desirable for the signature of the vehicle to follow the background as accurately as possible. The signature must here not always necessarily follow the air temperature. It is possible, in particular in deserts or other environments with little vegetation, to observe relatively great deviations of the ground temperature from the air temperature, to be precise in both directions.
Another solution is outlined in EP 1 574 809, where a metal foam is used as a heat exchanger and where air serves as a heat-transfer medium.
It is the object of the present invention to provide multispectral camouflage, which not only takes into account the improved sensor systems but also meets the requirements for high mobility.
According to the invention, a camouflage arrangement for adaptively camouflaging objects is proposed.
The proposal relates to at least one panel-like layer being used in the arrangement, through which panel-like layer air can flow, wherein the air which is taken in from the environment is regulatable, before or during the supply into the layer, to a temperature which has at least already been ascertained from the background of the object.
The solution developed in the present invention is based on adaptive, thermal camouflage for mobile, vehicle-bound platforms, possibly in combination with flexible radar absorbers. At its core, infrared sensors are used to continuously measure for example the entire environment) (360°) of the object, or the vehicle/platform, to be camouflaged and to segment in real time the information obtained and use it as a transmitter signal. Used as the adaptive camouflage material are various panels, such as in particular the abovementioned panel-like layer through which air can flow, which panels are individually brought dynamically to the corresponding temperature according to the background signal.
Each panel can in this case be connected to a radar absorber and be fabricated to fit perfectly to the object form or the vehicle form. The infrared signature generated is in this case independent from the object surface temperature and the environment air temperature and dynamically follows the background temperature.
To achieve optimum camouflage effect, the background is here measured using a radiometrically calibrated IR camera and the image is segmented or average values continuously calculated from individual image portions. These temperatures serve as measured value indicators for active camouflage.
The physical realization is based on cushions through which air flows, such as the panel-like layer through which air can flow, as mentioned in the introduction. Cold air is in this case taken in and electrically heated in the through-flow while it is being supplied to the respective air cushions. Each air cushion is regulated individually. A thermometer in the air cushions measures the respective temperature, which is then compared to the measured value indicator for this cushion and serves as feedback for controlling the heating.
The air can of course be supplied in a cooled state, either by using a dedicated air-conditioning system for the air cushions or, in the case of camouflage for a vehicle, by using a cold-air passage of the vehicle's air-conditioning system.
The construction of the camouflage arrangement was realized here as follows: on the vehicle-side, first tarpaulin material is wrapped around an insulating mat of, for example, cm thickness. This serves for isolating the active side from the surface temperature of the vehicle (e.g. engine space etc.). The layer, into which air is blown, is arranged on this insulating mat. Said air is allowed to escape upwards through a thin textile material, which is permeable to air. Said air-permeable material then outwardly exhibits the new signature in a thermal image. In order that the airflow during travel cannot influence the surface temperature of this material, the air cushion receives a third layer: separated by an air gap of about 2 cm from the air-permeable material, a for example thin polyethylene film is applied, which is so thin that it is transparent in IR and thus does not have its own signature. Heating by the sun or the action of the airflow during travel should not influence the signature of the cushion. The air escapes from the panel through air slits in the film.
In order to achieve radar camouflage in addition to the IR camouflage, the insulating mat can be interchanged or supplemented by a radar absorber.
Particular attention must be paid to the optimal air-guidance inside the panel: the inflowing air must spread out homogeneously as quickly as possible. This is achieved by air distributers made of flexible plastic hoses which have lateral openings for distributing the air quickly in the entire panel.
As shown above, the solution described here differs from today's commercially available mobile camouflage kits in that it actively matches the environment.
The proposed solution is distinguished from the solution described in EP 1 574 809 in that attention was paid to homogeneous and quick air distribution. Thereupon, the various camouflage areas (infrared and radar) are materially separate in the proposed solution according to the invention. An important aspect is that through use of an IR-transparent film the influence of the airflow during travel or the temperature of the airflow during travel is negated and it is thus possible to effectively achieve that the apparent temperature or signature of the panels can be matched to the measured apparent ambient temperature.